Dog Heat Cycle Calculator

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When a dog is in heat, it means she is in her fertile phase of the reproductive cycle. This is when her body is prepared for mating and she can become pregnant. You may notice behavioral and physical changes such as swelling of the vulva, bleeding, and increased attraction to male dogs.

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The dog heat cycle, also known as the estrous cycle, is the series of hormonal and physical changes a female dog undergoes to prepare for potential pregnancy. It includes four stages: proestrus, estrus, diestrus, and anestrus.

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Most female dogs experience their first heat cycle between 6 and 12 months of age, though it can vary by breed. Smaller breeds may start earlier, while larger breeds might have their first cycle closer to 18 months.

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On average, female dogs go into heat every 6 months, or about twice a year. However, this can vary based on breed, age, and individual factors. Smaller breeds may cycle more frequently, and larger breeds less often.

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The full heat cycle typically lasts about 2 to 4 weeks. The most fertile period usually occurs during the middle of this time, in the estrus stage.

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There are four stages: Proestrus (bleeding, swelling, attracting males), Estrus (fertile period, will accept males), Diestrus (post-heat recovery or pregnancy), and Anestrus (resting phase before the next cycle).

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Common signs include swelling of the vulva, bloody or pink discharge, increased urination, restlessness, mounting behavior, tail flagging, and increased affection or clinginess.

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Bleeding typically occurs during the proestrus stage and can last 7 to 10 days, though this may vary from dog to dog. Some dogs may have lighter or heavier bleeding.

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A dog can get pregnant during the estrus stage, which usually follows about 7–10 days after the start of bleeding. This is when she is fertile and will allow mating.

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Not exactly. While dogs do bleed during the heat cycle, it’s part of their reproductive process and not a monthly period like in humans. Dogs typically go into heat only twice a year.

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Yes, smaller breeds may experience their first heat as early as 6 months, while larger breeds may not start until 12–18 months. Genetics and individual development also play a role.

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Unlike humans, female dogs do not go through menopause. They continue to have heat cycles throughout their lives, although the cycles may become less regular with age.

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You may notice increased affection, restlessness, frequent urination, roaming tendencies, or even aggression. Some dogs may become more vocal or seek attention from male dogs.

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A dog is usually most fertile during the estrus stage, around days 10 to 14 of the cycle. She will show signs like softening of the vulva, lighter discharge, and receptiveness to male dogs.

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Keep her indoors and away from male dogs, use doggy diapers to manage discharge, clean her regularly, and provide comfort and calmness. Monitor her behavior and appetite for any changes.

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The most effective way is to have her spayed. Otherwise, keep her completely separated from male dogs during heat, including in public areas. Supervision is crucial as dogs can mate quickly.

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There is no medical benefit to letting your dog have a litter before spaying. In fact, spaying before the first or second heat significantly reduces the risk of mammary tumors and uterine infections.

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It’s technically possible, but not ideal. Spaying during heat can increase surgical risk due to elevated hormone levels and increased blood supply. Most vets recommend waiting until the cycle ends.

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Use reusable or disposable dog diapers, place washable covers on furniture, and regularly clean any soiled areas with pet-safe cleaners. Keeping her confined to easy-to-clean areas helps too.

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No, only female dogs experience heat cycles. However, unneutered male dogs can sense a female in heat from miles away and may become agitated, aggressive, or obsessive during this time.

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Yes, especially during the first few cycles or in older dogs. Some irregularity is normal, but if your dog misses multiple cycles or bleeds heavily or abnormally, consult your veterinarian.

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Yes. Unspayed dogs are at higher risk for uterine infections (pyometra), mammary tumors, false pregnancies, and behavioral issues. Spaying significantly reduces these risks.

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Male dogs can detect a female in heat from several miles away using scent. Even indoor dogs may attract unneutered males to your yard or home during her cycle.

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Calxify's Dog Heat Cycle Calculator helps you predict your dog’s next heat based on her last cycle. This is useful for planning breeding, scheduling vet visits, or simply managing care at home.